Method of and apparatus for economical use of mercury and other liquids



July 17,19 4. QHELD 1,966,442

METHOD OF AND APPARATUS FOR ECONOMICAL USE OF MERCURY AND OTHER LIQUI DS Original Filed Aug. 20, 1930 2 sheets-sheet 1 INVENTOR Craaby field i, BY

ATTORNEY y 1934- c. FIELD 1,966,442

METHOD OF AND APPARATUS FOR ECONOMICAL USE OF MERCURY AND OTHER LIQUIDS Original Fil ed Aug. 20, 1930 2 Sheets-Sheet 2 1: .Z. Y W X )V M a 1 .5. V A/ ia/W L INVENTOR Crqsy Field BY @ZM 4 ATTORNEY Patented July 17, 1934 PAT ENT OFFICE METHOD OF AND APPARATUS FoR ECO-' NOMICALUSE or MERCURY AND OTHER LIQUIDS Crosby Field, Brooklyn, Y.

Application August 20, 1930, Serial No. 476,488 1 Renewed October 10, 1933 16 Claims.

My present invention relates primarily to the boiling and condensing of pure mercury for heat transfer purposes, but it is directly applicable to the boiling and condensing of other liquids -\,having similar characteristics including high boiling point, low freezing point, great weight per unit volume, great surface tension, and par similarly the quality of not wetting and not having any interaction with respect to ferrous metal such as iron, steel and 'many alloys thereof. However, substantially pure mercury has the desired characteristics in the greatest degree, and in order to utilize these desirable characteristics and also because pure mercury; is relatively expensive, designers'of mercury boilers have taken pains to makethe mercury surface exposed to the heating surface as great as possible per unit volume of mercury. In order to accomplish this,

the heating surface has s'cmetimesbeen made in the form of small tubes, frequently depending closed ended tubes with interior fillers, usually innertubes of metal or insulating material designed so' as to leave only a-small annular space for the mercuryto fill and in which it is vaporized (see my'prior Patents 1,619,660 and 1,619,663,

granted March 1 1927, and patent to Short 1,633,319, granted September 4, 1928). p 7

Because of the above de scribed peculiarities of mercury as aliquid, particularly great weight and ,surface tension, no wetting or other interaction between it and ferrous metals, as well as on account-of expense, the modern art has worked out above arrangements'for great heating surface per unit volume, but such a practice is found to introd'uceoth'er"difficulties which it is anobj'ect of my present invention to solve. For instance, where the column of boiling mercury is deep enough to'aiford depth pressure which: isdesirable forforcing the mercury promptly into 9 contact with the heating surface, and after a" vapor bubble has formed, the vaporizedmer-- art has been developing to its present success, no one has ever considered it possible to get the desiredgreat area of exposed surface and the desired depth pressure, necessary to insure prompt inflow of the liquid mercury to replace the vapor bubbles, otherwise than by solid fillers,- opposing practically'no flow resistance to the mercury. 1 r 7 Nevertheless, I have discovered the possibility of, and have successfully employed, my present method of boiling of the mercury'at" an eiiective depth pressure equal to that afforded by a much larger volume, without interfering with the boiling, nor the prompt replacement 'of the vapor by the liquid, and without introducing anynew difliculty.

More specifically, I have discovered that much improved conditions may be obtained in any mercury boiler by making the mercury containing spaces relatively large and filling part or all of the space with amaterial readily permeable by mercury. and mercury vapor, preferably steel wool felted and compressed'to such degreeas may be necessary-to suit conditions. Instead of steel wool, steel filaments or wires; or wool, fila-' ments or wires of other ferrous metals mayb used Ferrous metals have the advantage that there is' no interaction between them and mercury, but while mercury does form amalgams with some of the non-ferrous metals, this may not prevent use of certain ferrous metal alloys that may contain a percentage of a non-ferrous metal. However, preferably and by way of illust'rationof my present invention, I have selected steel wool and prefer to employ it with relatively pure mercury such that there isno chemical interaction whatever, and the mercury does'not wet the wool. I Among the advantages ofsteel' wool as a filler inboilers'ior vaporizing mercury are: (a) it can be felted and compressed into bats of any desired shape; (b) its density maybe varied within wide limits, by selection of the grade (size) of wool and-the amount of compression; (0) the mere curyboil'e r heating elements may be built up uti-' lizing bats of varying density, using the lighter in those'pa'rts when the mercury is mostly in the vapor phase; (d) steel wool is a conductor of heat, especially when compressed; the greater the compression the'greater the conductivityvery-loose or fiuil'y wool is so poor'that it can be classed as an insulator; -(e) wool compressed to a density equal'to or the density of steel is an excellentconductor; compressions in be-i tween give conductivities between these limits, but

not exactly proportional, the conductivity increasing much faster than the density; (1) it presents a large surface to the mercury, and because of its fibrous mass it breaks up any large bubbles of boiling liquid, separating out thevapor and returning the liquid to themain body of boiling liquid, thus greatly improving, merely byits .presence, boiling conditions; (9) it is relatively'cheap, costing about one-tenth the price of mercury; (h) it is thoroughly resilent, hence takes care of all its expansion strains due to temperature without noticeably increasing the stresses in the boiler parts; and (2') it has filtering properties.

As purchased in the retail stores, the finer grades of steel wool have a density of about 0.004 pounds per cubic inch. This can readily be increased by a screw press to 0.017 pounds per cubic inch and by hydraulic pressing to as high as 0.20 pounds per cubic inch, the latter density being about five-sevenths that of drawn steel. For use in mercury boilers, -I prefer to use a coarse grade, No. 3 or coarser, and. to vary the density from 0.04 to 0.16 pounds per cubic inch, only occasionally going to greater compressions than 0.16 pounds. With 0.04 density the space remaining to be filled by mercury will be 85%; while with 0.16 this has been reduced to 43%; or amount of mercury has been reduced one-half, without causing appreciable obstruction to free flow of the mercury.

The above and other features of my invention will be more evidentfrom the following description in connection with the accompanying drawings, in which Fig. 1 is longitudinal section showing somewhat diagrammatically a heat transfer systemincluding a boiler of the tubular type showing the filler therein;

Fig. 2 is a sectional detail taken on line 22, Fig. 1;

Fig. 3 is a detail view showing the configuration of the fillers for such a boiler;

Fig. 4 is a detail view of the finger type of mercury vapor boiler; and r j Fig. 5 is an enlarged sectional view showing the construction of a finger containing a filler of my invention. 1 a

Like characters of reference indicate like parts throughout the several views of the drawings.-

Referring to the drawings wherein the preferred embodiment of my invention is setforth,

there is shown a horizontal return tubular mercury vapor boiler 6, set in a conventionally indicated furnace comprising brick work casing '7, heated by a burner 8 supplied with fuel by a pipe 9, the path of the flame and flue gases being designated by arrows 11. Heating tubes 12 are secured to the end plates 13, 14 of the boiler in any suitable manner, as by welding. In constructing the boiler, the filler sections 15 and 16 are inserted in the boiler about the heating tubes before the end plate 13 is welded in position.

These fillers may consist of metal wool filaments or wires, preferably steel wool, which may be compressed enough to set the fibers and give the filler a more or lessdefinite, self-retaining form.

The bats are shown as retained in position by bars 17 which may be secured to the shell or the boiler by welding. However, welding is unnecessary as the resilience and floating tendency of the steel wool will ordinarily hold the bars in place.

The vaporized mercury is caught in a dome 18 formed in the shell of the boiler and is led off through'a conduit 19 to the point of heat utilization which in the illustrated embodiment is a re-' tort or evaporator vessel 21' having ajacket 22 in which the mercury vapor is condensed, the liquid returning through a pipe 23 to a filter 24 having a removable cover 25. As a filtering medium I employ a moderately compressed mass of steel wool 25' which I have found to be admirably suited for the purpose. A pipe 26 leads the liquid to the bottom of the boiler. It is' to be understood that the mercury may be utilized for other purposes, for example, to operate a mercury vapor turbine or other mechanical power producing engine.

In Figs. 4 and 5, there is shown a mercury vapor boiler of the well-known finger type wherein my invention may be applied. The reference .character 27 indicates a boiler having welded therein the vertically disposed finger tubes 28. Extending through the boiler is a header 29, having suitably fixed thereto thick metal tubes 31 which are adapted to enter fingers 28. The space between the finger 28 and the tube 31 is filled with bats 32, 33, 34 and 35, of preformed felted steel wool compressed to predetermined densities which are determined by operating conditions. Lugs 36 are adapted to hold the bats in place in the fingers. Steel wool bats may also be placed in the header .29 for space filling or filtering purposes.

In operation, enough liquid mercury is placed in the system to insure suflicient hydrostatic head to maintain the heat transfer surfaces always in contact with liquid mercury. The liquid mercury is fed to header 29 from return pipe 37 and distributed to the fingers through conduit 38 in tubes 31, the liquid flowing to the bottom of the fingers, thence up through thersteel wool fillers in the space between finger 28 and tube 31, emerging as vapor in boiler 27. The vapor is led out through dome 41 and pipe 42 to the point of heat utilization (not shown), the condensate returning through pipe 3'7.

. Inthe construction outlined above, the fillers of my invention not only serve as a means of reducing the quantity of mercury required in mercury heat transfer systems, but also as a separator for mercury liquid and vapor and as an aid to quieter boiling; and in addition it also serves as an elastic spacer between the filler tubesand the walls of their containers thus preventing displacement and deformation of said tubes such as is likely to be caused by expansion where said spacers are used.

It will be understood that my invention may also be used with any amalgam of low boiling point which will evaporate.

- From the foregoing, it will be evident that my invention is applicable to apparatus in which a relatively smallv amount of liquid, particularly expensive liquid, particularly mercury, is used and in which the use involves utilization of the depth pressure of the liquid, or exposure of large surface, per unit volume thereof. It is also applicable to promote non-turbulent evolution and separation of vapor from boiling liquid, particularly in narrow spaces for a substantial depth below the surface of the liquid. It is also applicable for its function as an elastic separator interposed in narrow interspaces between adjacent surfaces. It will be noted that in the finger form of boiler shown in Figs. 4 and 5, all of these functions are served simultaneously by the compressed steel wool spacers.

Furthermore, all of said functions except that of non-turbulent I boiling will be served when either of the boilers herein shown, particularly that of Figs. 4 and 5, isused as a cooler either to condense mercury vapor or to cool mercury liquid. When so used, a suitable cooling medium, gaseous or liquid, will be substituted for the flame and products of combustion which are employed when the apparatus is used for boiling.

I claim: 7

1. A method of causing a given volume of boiling mercury to have the effective depth pressure and volume of a much larger amount, which method includes filling the mercury containing space to a desired extent with ferrous metal wool and preventing the latter from floating on the mercury.

2. A method of heating mercury and facilitating evolution and separation of vapor therefrom, which includes increasing the effective volume and resulting depth pressure and exposed contact area of the mercury by filling the space in which the mercury is boiled with a freely permeable mass of filamentary heat-conducting material that does not amalgamatewith mercury.

3. A method of heating mercury and facilitating evolution and separation of vapor therefrom, which includes increasing the effective volume and resulting depth pressure and exposed contact area of the mercury by filling the space in which the mercury is boiled with a freely permeable mass of filamentary heat-conducting material that does not amalgamate with mercury formed to the shape of said space.

4. A method of causing a given volume of mercury to have the effective depth pressure and volume of a much larger amount, which method includes filling the mercury containing space to a desired extent with compressed steel wool, and preventing the latter from floating on the mercury.

5. A method of causing a given volume of mercury to have the effective depth pressure and volume of a much larger amount, which method includes filling the mercury containing space to a desired extent with compressed steel wool, and preventing the latter from floating on the mercury, said steel wool being compressed more densely at the lower levels than at the higher levels.

6. A method of increasing the effective volume and resulting depth pressure and exposed contact area of a mercury-like liquid, which includes filling the space to be occupied by the liquid with a freely permeable, filamentary, heat-conducting material that is chemically inert to said liquid.

'7. A method of increasing the effective volume and resulting depth pressure and exposed contact area of a mercury-like liquid, which includes filling the space to be occupied by the'liquid with a freely permeable, filamentary, heat-conducting material that is chemically inert to said liquid and which is formed tothe shape of said space.

8. Apparatus including a container, and mercury-like liquid in said container; said apparatus including means for utilizing, and said container being formed with liquid containing space having relatively large surface contact area and substantial depth pressure of the liquid in combina- 7 tion with a filler in the liquid, containing space consisting of filamentary metal that is chemically inert to said liquid.

9. Apparatus including a container, and mercury-like liquid in said container that is substantially without chemical affinity for steel; said apparatus including means for utilizing, and said container being formed with liquid containing space having relatively large surface contact area and substantial depth pressure of the liquid in combination with a filler in the liquid containing space consisting of compressed steel wool.

10. Apparatus including a container, and mercury in said container; said apparatus including means for utilizing, and said container being formed with liquid containing space having relatively large surface contact area and substantial depth pressure of the mercury in combination with a filler in the liquid containing space consisting of a formed mass of filamentary metal of a class that does not amalgamate with mercury.

11. Apparatus including a container, and mercury in said container; said apparatus including means for utilizing, and said container being formed with liquid containing space having relatively large surface contact area and substantial depth pressure of the mercury in combination with a filler in the liquid containing space consisting of compressed steel wool.

12.. Apparatus including a container, and mercury therein; said container having a mercury containing space designed for a substantially greater amount of mercury, and affording corresponding depth pressure and surface area of said mercury, in combination with a mass of ferrous metal wool displacing a substantial part of said mercury to give a smaller amount of liquid the effect of a large volume depth pressure and surface contact.

13. Apparatus including a container, and mercury therein; said container having a mercury containing space designed for a substantially greater amount of mercury, and affording corresponding depth pressure and surface area of said mercury, in combination with a mass of ferrous metal wool displacing a' substantial part of said mercury to give a smaller amount of liquid the effect of a large volume depth pressure and surface contact and means for preventing said wool from floating on the mercury.

14. A boiler for vaporizing liquids, including aplurality of concentric tubes and means retaining the inner tubes in position comprising interposed compressed metal wool.

15. A boiler for vaporizing liquids, including a plurality of depending concentric tubes, and means for retaining said tubes in position comprising an interspace filler of compressed metal wool of greater density at the bottom than at the top.

16. In a boiler for vaporizing liquids, including a plurality of tubes, means for retaining said tubes in position comprising a plurality of preformed annular cylindrical bats of compressed metal wool.

CROSBY FIELD. 

